lkml.org 
[lkml]   [2006]   [Sep]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[RFC, PATCH 8/9] CPU Controller V2 - task_cpu(p) needs to be correct always
    We rely very much on task_cpu(p) to be correct at all times, so that we can
    correctly find the task_grp_rq from which the task has to be removed or added
    to.

    There is however one place in the scheduler where this assumption of
    task_cpu(p) being correct is broken. This patch fixes that piece of code.

    (Thanks to Balbir Singh for pointing this out to me)

    Signed-off-by : Srivatsa Vaddagiri <vatsa@in.ibm.com>

    ---

    linux-2.6.18-root/kernel/sched.c | 10 ++++++++--
    1 files changed, 8 insertions(+), 2 deletions(-)

    diff -puN kernel/sched.c~cpu_ctlr_setcpu kernel/sched.c
    --- linux-2.6.18/kernel/sched.c~cpu_ctlr_setcpu 2006-09-28 16:40:37.844287616 +0530
    +++ linux-2.6.18-root/kernel/sched.c 2006-09-28 17:23:14.896556584 +0530
    @@ -5230,6 +5230,7 @@ static int __migrate_task(struct task_st
    {
    struct rq *rq_dest, *rq_src;
    int ret = 0;
    + struct prio_array *array;

    if (unlikely(cpu_is_offline(dest_cpu)))
    return ret;
    @@ -5245,8 +5246,8 @@ static int __migrate_task(struct task_st
    if (!cpu_isset(dest_cpu, p->cpus_allowed))
    goto out;

    - set_task_cpu(p, dest_cpu);
    - if (p->array) {
    + array = p->array;
    + if (array) {
    /*
    * Sync timestamp with rq_dest's before activating.
    * The same thing could be achieved by doing this step
    @@ -5256,6 +5257,11 @@ static int __migrate_task(struct task_st
    p->timestamp = p->timestamp - rq_src->timestamp_last_tick
    + rq_dest->timestamp_last_tick;
    deactivate_task(p, rq_src);
    + }
    +
    + set_task_cpu(p, dest_cpu);
    +
    + if (array) {
    __activate_task(p, rq_dest);
    if (TASK_PREEMPTS_CURR(p, rq_dest))
    resched_task(rq_dest->curr);
    _
    --
    Regards,
    vatsa
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/
    \
     
     \ /
      Last update: 2006-09-28 19:37    [W:2.497 / U:0.996 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site